Tuesday, January 16, 2018

30 Linux System Monitoring Tools Every SysAdmin Should Know

https://www.cyberciti.biz/tips/top-linux-monitoring-tools.html

Need
to monitor Linux server performance? Try these built-in commands and a
few add-on tools. Most distributions come with tons of Linux monitoring
tools. These tools provide metrics which can be used to get information
about system activities. You can use these tools to find the possible
causes of a performance problem. The commands discussed below are some
of the most fundamental commands when it comes to system analysis and
debugging Linux server issues such as:

Finding out system bottlenecks

Disk (storage) bottlenecks

CPU and memory bottlenecks

Network bottleneck.

1. top – Process activity monitoring command

top
command display Linux processes. It provides a dynamic real-time view
of a running system i.e. actual process activity. By default, it
displays the most CPU-intensive tasks running on the server and updates
the list every five seconds.Fig.01: Linux top command

Commonly Used Hot Keys With top Linux monitoring tools

Here is a list of useful hot keys:

Hot Key

Usage

t

Displays summary information off and on.

m

Displays memory information off and on.

A

Sorts
the display by top consumers of various system resources. Useful for
quick identification of performance-hungry tasks on a system.

f

Enters an interactive configuration screen for top. Helpful for setting up top for a specific task.

4. uptime – Tell how long the Linux system has been running

uptime
command can be used to see how long the server has been running. The
current time, how long the system has been running, how many users are
currently logged on, and the system load averages for the past 1, 5, and
15 minutes.# uptime Output:

18:02:41 up 41 days, 23:42, 1 user, load average: 0.00, 0.00, 0.00

1
can be considered as optimal load value. The load can change from
system to system. For a single CPU system 1 – 3 and SMP systems 6-10
load value might be acceptable.

5. ps – Displays the Linux processes

ps command will report a snapshot of the current processes. To select all processes use the -A or -e option:# ps -A Sample Outputs:

8. sar – Monitor, collect and report Linux system activity

sar command used to collect, report, and save system activity information. To see network counter, enter:# sar -n DEV | more The network counters from the 24th:# sar -n DEV -f /var/log/sa/sa24 | more You can also display real time usage using sar:# sar 4 5 Sample Outputs:

11. netstat – Linux network and statistics monitoring tool

12. ss – Network Statistics

ss
command use to dump socket statistics. It allows showing information
similar to netstat. Please note that the netstat is mostly obsolete.
Hence you need to use ss command. To ss all TCP and UDP sockets on
Linux:# ss -t -a OR# ss -u -a Show all TCP sockets with process SELinux security contexts:# ss -t -a -Z See the following resources about ss and netstat commands:

16. htop – interactive process viewer

htop
is a free and open source ncurses-based process viewer for Linux. It is
much better than top command. Very easy to use. You can select
processes for killing or renicing without using their PIDs or leaving
htop interface.$ htop Sample outputs:

17. atop – Advanced Linux system & process monitor

atop
is a very powerful and an interactive monitor to view the load on a
Linux system. It displays the most critical hardware resources from a
performance point of view. You can quickly see CPU, memory, disk and
network performance. It shows which processes are responsible for the
indicated load concerning CPU and memory load on a process level.$ atop

20. nethogs- Find out PIDs that using most bandwidth on Linux

NetHogs
is a small but handy net top tool. It groups bandwidth by process name
such as Firefox, wget and so on. If there is a sudden burst of network
traffic, start NetHogs. You will see which PID is causing bandwidth
surge.$ sudo nethogsLinux: See Bandwidth Usage Per Process With Nethogs Tool

27. Nagios – Linux server/network monitoring

Nagios
is a popular open source computer system and network monitoring
application software. You can easily monitor all your hosts, network
equipment and services. It can send alert when things go wrong and again
when they get better. FAN is
“Fully Automated Nagios”. FAN goals are to provide a Nagios
installation including most tools provided by the Nagios Community. FAN
provides a CDRom image in the standard ISO format, making it easy to
easilly install a Nagios server. Added to this, a wide bunch of tools
are including to the distribution, in order to improve the user
experience around Nagios.

28. Cacti – Web-based Linux monitoring tool

Cacti
is a complete network graphing solution designed to harness the power
of RRDTool’s data storage and graphing functionality. Cacti provides a
fast poller, advanced graph templating, multiple data acquisition
methods, and user management features out of the box. All of this is
wrapped in an intuitive, easy to use interface that makes sense for
LAN-sized installations up to complex networks with hundreds of devices.
It can provide data about network, CPU, memory, logged in users,
Apache, DNS servers and much more. See how to install and configure Cacti network graphing tool under CentOS / RHEL.

29. KDE System Guard – Real-time Linux systems reporting and graphing

KSysguard
is a network enabled task and system monitor application for KDE
desktop. This tool can be run over ssh session. It provides lots of
features such as a client/server architecture that enables monitoring of
local and remote hosts. The graphical front end uses so-called sensors
to retrieve the information it displays. A sensor can return simple
values or more complex information like tables. For each type of
information, one or more displays are provided. Displays are organized
in worksheets that can be saved and loaded independently from each
other. So, KSysguard is not only a simple task manager but also a very
powerful tool to control large server farms.Fig.05 KDE System Guard {Image credit: Wikipedia}See the KSysguard handbook for detailed usage.

30. Gnome Linux system monitor

The
System Monitor application enables you to display basic system
information and monitor system processes, usage of system resources, and
file systems. You can also use System Monitor to modify the behavior of
your system. Although not as powerful as the KDE System Guard, it
provides the basic information which may be useful for new users:

Displays various basic information about the computer’s hardware and software.

Linux Kernel version

GNOME version

Hardware

Installed memory

Processors and speeds

System Status

Currently available disk space

Processes

Memory and swap space

Network usage

File Systems

Lists all mounted filesystems along with basic information about each.

Fig.06 The Gnome System Monitor application

Bonus: Additional Tools

ntop
web based tool – ntop is the best tool to see network usage in a way
similar to what top command does for processes i.e. it is network
traffic monitoring software. You can see network status, protocol wise
distribution of traffic for UDP, TCP, DNS, HTTP and other protocols.

Conky
– Another good monitoring tool for the X Window System. It is highly
configurable and is able to monitor many system variables including the
status of the CPU, memory, swap space, disk storage, temperatures,
processes, network interfaces, battery power, system messages, e-mail
inboxes etc.

GKrellM
– It can be used to monitor the status of CPUs, main memory, hard
disks, network interfaces, local and remote mailboxes, and many other
things.

mtr – mtr combines the functionality of the traceroute and ping programs in a single network diagnostic tool.